jonis:
I'm currently running SMF 1.1.16, also running TinyPortal and a few more mods.

My problem is that when any user, including me, tries to fill in the "To"-field when sending a PM, it after the very first letter typed gets autofilled with one specific member. Always the same member and no matter how many more letters you enter it's stuck at this member. You can ofc get around it by pasting a complete user in the field or grabbing through the search method.

This occurs in any browser. Tried FF 10.0.2, Chrome and IE.

I've tried to replace the PersonalMessage.template.php in .../Themes/default with a fresh one from 1.1.16 install package, no difference. There's no errors in the log and my forum works fine besides this.

What could be a possible culprit? Any ideas as to where to continue looking?

Kermit:
As far as i know there is no auto fill function in SMF's Personalmessage system ,that's why it can be only browser related issue

Illori:
yes smf has an auto fill function for names when sending a pm. if it is not working then one or more of your files may have been edited. any errors in your error log?